Attachment enhanced 293 cells

ABSTRACT

Attachment enhanced human embryonic kidney cells, 293, are provided. These cells have been modified to contain a selected mammalian scavenger gene, which has been found to improve the ability of these cells to attach in culture. The improved cells of the invention are useful in assays in which the unmodified 293 cells could be used.

CROSS-REFERENCE TO RELATED APPLICATIONS

This instant application was filed under 35 U.S.C. §371 as the national stage application of PCT/US96/08081, filed on May 30, 1996, and is a continuation of U.S. application Ser. No. 08/453,117, filed on May 30, 1995, now U.S. Pat. No. 5,683,903.

FIELD OF THE INVENTION

This invention relates generally to cell lines used in the recombinant production, screening or measurement of protein or protein interactions in vitro.

BACKGROUND OF THE INVENTION

The primary human embryonic kidney (HEK) 293 cell line is a permanent line of cells transformed by sheared human adenovirus type 5 (Ad 5) DNA. The cells are particularly sensitive to human adenovirus, are highly permissive for adenovirus DNA, and contain and express the transforming genes of Ad5. This is a hypotriploid human cell line. See, F. Graham et al., J. Gen. Virol., 36:59-72 (1977); T. Harrison et al., Virology, 77:319-329 (1977).

This cell line, which is readily available from commercial sources, such as the American Type Culture Collection, is used extensively in in vitro assays, and for the production of recombinant proteins and viruses. However, in washing steps which are conventionally and repeatedly employed in such in vitro assays and other manipulations of these cells, the cells readily detach or are washed away from the plates or dishes in which the studies are performed. This problem typically results in inaccurate, unreliably low measurement or collection of the protein, peptide or interaction to which the assay is directed.

There remains a need in the art for a cell substrate useful in in vitro manipulations in genetic engineering, which permits the measurement of accurate results.

BRIEF SUMMARY OF THE INVENTION

In one aspect, the invention provides improved HEK 293 cells, which cells are 293 cells which have been transfected with a mammalian macrophage scavenger receptor gene. Preferably, this gene is the human Type I or II macrophage scavenger receptor gene SEQ ID NOS: 1 or 3!.

In another aspect, the invention provides a method of enhancing the ability of HEK 293 cells to attach in tissue culture. This method involves the steps of transfecting 293 cells with a selected mammalian macrophage scavenger receptor gene.

In yet another aspect, the invention provides a method of screening compounds for biological activity which involves screening the improved 293 cells of the invention. In this method, the improved 293 cells have been further transfected with a selected gene and are then screened for expression of the selected gene. The cells expressing the selected genes are incubated in the presence of a compound of unknown biological activity, and then screened for the ability of the compound to affect the expressed gene product or its function.

Other aspects and advantages of the present invention are described further in the following detailed description of the preferred embodiments thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A to 1C provide the nucleic acid SEQ ID NO: 1! and amino acid SEQ ID NO:2! sequences of the human macrophage scavenger receptor type I.

FIGS. 2A and 2B provide the nucleic acid SEQ ID NO:3! and amino acid SEQ ID NO:4! sequences of the human macrophage scavenger receptor type II.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides an improved human embryonic kidney cell line, 293. The inventors have surprisingly found that human embryonic kidney (HEK) 293 cells transfected with a mammalian macrophage scavenger receptor gene demonstrate an enhanced ability to attach to a solid support as compared to conventional, unmodified 293 cells. In contrast to unmodified 293 cells, the improved 293 cells of the invention are not as readily washed away as unmodified 293 cells under the normal conditions of biological assays. Thus, the improved 293 cells of the invention are particularly well suited for use in in vitro studies and other applications for which unmodified 293 cells may be used.

As used herein "solid support" is any surface used for culturing, for in vitro assays, and the like. For example, a typical solid support is a plastic tissue culture plate, or a multi-well plate, hollow fibers, a test tube, conventionally employed plastic beads, glass beads, etc. Other solid supports are well known to those of skill in the art.

By "enhanced ability to attach" is meant that the transfected cells of this invention attach to the solid support with sufficient avidity to resist detachment which normally occurs with untransfected 293 cells caused by assay washing steps with buffer or growth medium. More specifically, the transfected cells of this invention because of the characteristic of enhanced attachment provide results of, for example, five times the cell number remaining after two washes as compared to the number of cells remaining following two washes of untransfected cells.

The human embryonic kidney cell line, 293, is readily available from the American Type Culture Collection, 12301 Parklawn Drive, Rockville, Md., U.S.A., under accession number ATCC CRL 1573. Also encompassed by this invention are progeny and derivatives of this cell line, which may be prepared using conventional techniques. See, Sambrook, Molecular Cloning: A Laboratory Manual, 2d ed., Cold Spring Harbor Press, Cold Spring Harbor, N.Y. (1989).

According to this invention, these cells are modified by transfection with a selected mammalian macrophage scavenger receptor (MSR) gene. Currently, in a preferred embodiment, this gene is selected from a human MSR Type I or Type II gene, and most preferably, the gene is characterized by the sequence provided in GenBank, under accession number D90187 (MSR Type I) or D90188 (MSR Type II). The sequences SEQ ID NO:1 and 2! of MSR Type I are provided in FIG. 1. The sequences SEQ ID NO:3 and 4! of MSR Type II are provided in FIG. 2. Both of these genes were obtained from the human monocytic cell line THR-1 following four days of phorbol ester treatment. These two gene sequences are differential splice variants of a single human gene, and are described in more detail in A. Matsumoto et al., Proc. Natl. Acad. Sci. USA, 87:9133-9137 (1990), incorporated by reference herein.

It is anticipated that non-human homologs of MSR I or MSR II will be similarly useful in preparing the improved 293 cells according to the invention. Particularly desirable are the bovine T. Kodama et al., Proc. Natl. Acad. Sci. USA, 85:9238-9242 (1988)!, murine M. Freeman et al., Proc. Natl. Acad. Sci. USA, 87:8810-8814 (1990)! and rabbit P. E. Bickel and M. W. Freeman, J. Clin. Invest., 90:1450-1457 (1992)! homologs, each of which is at least 60-80% homologous with the human MSR genes. It is further anticipated that other human scavenger receptor genes, particularly other genes which are produced recombinantly or are differentially selective for oxidized or acetylation-modified low density lipoprotein (LDL) species or another desired lipoprotein species, will be similarly useful.

One of these genes, preferably a human MSR gene, is selected and cloned into an appropriate vector for use in transfecting the 293 cells. Generally, a suitable expression vector is one which contains control or regulatory sequences operably linked with the nucleic acid sequences of the gene. These regulatory sequences are capable of directing the expression of the gene product in the 293 cells. Suitable vectors and regulatory sequences are well known to those of skill in the art and this invention is not limited by the selection thereof.

For example, suitable vectors may be, or contain components from, viral vectors selected from simian virus SV40, retroviruses, bovine papilloma virus, vaccinia virus, and adenovirus, or commonly used bacterial vectors or commonly used mammalian expression vectors or integrative vectors which lead to a stable expression cell line. The vector used in the examples below is pCDN N. Aiyar et al., Mol. Cell. Biochem., 131:75-96 (1994)!, which contains the promoter from cytomegalovirus, followed by a polycloning site and a polyadenylation site, the SV40 early enhancer, the human gene for dihydrofolate reductase, and a gene conferring resistance to neomycin.

Methods for introduction of a vector containing an MSR gene into mammalian cells are well known. Examples of suitable methods include, without limitation, dextran-mediated transfection, calcium phosphate precipitation, polybrene mediated transfection, protoplast fusion, electroporation, encapsulation of the polynucleotide(s) in liposomes, and direct microinjection of the DNA into nuclei.

Sequences which contain selectable markers may also be transfected into the cell line. These markers may be contained on the vector containing the MSR gene, or may be separately transfected using conventional techniques, such as those described herein. Selectable markers for mammalian cells are known in the art, and include for example, thymidine kinase, dihydrofolate reductase (together with methotrexate as a DHFR amplifier), aminoglycoside phosphotransferase, hydromycin B phosphotransferase, asparagine synthetase, adenosine deaminase, metallothionien, and antibiotic resistant genes such as neomycin. Other markers may be readily selected by one of skill in the art, as desired.

As described in more detail below, if the MSR transfected cell is desired for use in a screening assay, the cell may also be transfected with other genes. The additional gene(s) may, for example, encode a protein which will be screened for biological activity or for interaction with the MSR or another transfected gene.

Following transfection with the selected MSR gene (and optionally, any other gene), the cells are incubated in a suitable selection medium, e.g., Eagles MEM, Dulbecco's MEM or the like.

Once modified to contain the MSR gene, or another suitable gene, according to the methods described above, the improved 293 cells are particularly well suited for use in any assay in which an unmodified 293 cell may be used. However the use of the improved 293 cells of the invention will result in superior attachment, and thus, more accurate test results.

An exemplary use of the improved 293 cells of the invention includes the use of these cells in a method of screening compounds for biological activity. This method involves the use of the attachment enhanced 293 cells of the invention which have been further transfected with a selected gene sequence. These cells are subsequently screened for expression of the selected gene. The cells expressing these selected genes are then incubated in the presence of a compound of unknown biological activity and further assayed for the ability of the compound to affect the expressed gene product.

Similarly, the attachment enhanced 293 cells of the invention may be used to identify antagonists of the MSR gene, i.e., to develop agents for atherosclerosis. Suitable assays for identifying antagonists to an expressed gene product are well known to those of skill in the art. See, T. Kodama et al., Nature, 343:531-535 (1990), A. M. Pearson et al., J. Biol. Chem., 268:3554 (1993).

The surprising result of enhanced attachment demonstrated by 293 cells transfected with MSR genes is not demonstrated when other cells, such as Chinese Hamster Ovary (CHO) cells, are transfected with MSR I or MSR II. To the inventors' knowledge, no other cell line has demonstrated this result when transfected with MSR genes.

The following examples illustrate the preferred methods for preparing the modified 293 cells of the invention and uses therefor. These examples are illustrative only and are not intended to limit the scope of the invention.

EXAMPLE 1 Calcium Phosphate Transfection of Macrophage Scavenger Receptor I and into Human Embryonic Kidney 293 Cells

The macrophage scavenger receptor I or II cDNAs SEQ ID NO:1 and 3, respectively! were subcloned into the mammalian expression vector pCDN in the correct orientation N. Aiyar, Mol. Cell. Biochem., 131:75-86 (1994)!.

The resulting construct containing the macrophage scavenger receptor I or II cDNA was used to transfect human embryonic kidney (HEK) 293 cells by calcium phosphate transfection. One day prior to the transfection, the HEK 293 cells were plated into 10 cm dishes at a density of 2×10⁵ cells, so that the cells would be approximately 10% confluent within 24 hours. The cells were seeded into Eagle's Minimal Essential Medium (EMEM) supplemented with 2 mM L-glutamine and 10% fetal bovine serum (FBS).

The DNA was prepared for transfection by sterile ethanol precipitation. Following ethanol precipitation, the DNA pellet was dried inside a tissue culture hood. The pellet was then resuspended in 450 μL of sterile water and 50 μL of 2.5 M CaCl₂. Ten μg of DNA were used per 10 cm dish. While gently swirling the DNA mixture, 500 μL of sterile 2×BBS (50 mM N,N-bis 2-hydroxyethyl-2-aminoethane sulfonic acid, 280 mM NaCl₂ and 1.5 mM NaHPO₄) was added. The BBS/DNA-CaCl₂ solution was allowed to form a precipitate by sitting at room temperature for 10-20 minutes.

The solution was then gently mixed to ensure adequate suspension of the precipitate and then added dropwise into the 10 cm dish of cells. The plate was gently swirled to distribute contents evenly. After a 12-16 hour incubation, the medium was carefully removed, and the cells were washed once with 5 ml of PBS (without Ca²⁺ or Mg²⁺) followed by the addition of 10 ml of EMEM supplemented with 2 mM L-glutamine and 10% FBS.

Following an overnight incubation, the medium was removed, and the cells were carefully washed once with 5 ml of PBS (without Ca²⁺ or Mg²⁺). To initiate selection, 10 ml of fresh EMEM with L-glutamine supplemented with 2 mM L-glutamine, 10% FBS and 0.4 mg/ml of geneticin (GIBCO-BRL) were added. Two or three days later, the medium was changed.

After approximately 2-3 weeks, each plate was examined under the microscope for small patches of growing cells. The patches were grown large enough to be seen as small spots on the bottom of the plate. Once at this stage, all of the medium was removed and 3 μL of trypsin was added directly to the patch of cells. By pipetting up and down several times, the patch of cells was transferred to a 24 well dish containing 1 ml of medium with geneticin. The cells were expanded from this 24 well stage to a 6 well plate or T-25 Flask. Because the 293 cells grow best in conditioned medium, cells were fed based on their rate of growth, but typically not more than once a week.

EXAMPLE 2 Comparison of Transfected and Untransfected 293 Cells

To demonstrate the surprising results of the above transfection, and the greater accuracy obtained in using the transfected 293 cells in assays, transfected 293 cells of this invention and untransfected 293 cells were seeded at the same cell density (100,000 per well) into 24-well plastic tissue culture dishes. These cells were allowed to grow for two days before testing. Cell growth appeared to be equivalent.

The same biochemical assay was performed on the transfected and untransfected cells.

The presence of macrophage scavenger receptors was confirmed by incubating transfected 293 cells with ¹²⁵ I!-acetylated LDL at a concentration of approximately 5 μg/ml (specific activity ˜100-300 cpm/ng protein) for 5 hours at 37° C., essentially as described in J. Ashkenas et al., J. Lipid Res., 34:983-1000 (1993). In replicate experiments, ¹²⁵ I!-acetylated LDL binding/uptake amounted to an average of 1.75 μg/mg protein (n=76). Where it has been possible to measure ¹²⁵ I!-acetylated LDL binding/uptake to untransfected 293 cells, the average was 0.20 μg/mg protein (n=6). After the assays were performed on the cells, they were dissolved in 0.1 M NaOH, and aliquots were used to determine total protein concentration by the Pierce BCA assay with bovine serum albumin as the standard. In an attempt to keep as many untranfected cells as possible attached to the culture dished, the untransfected cells were washed only twice, while the transfected cells were washed seven times as per the procedure cited above.

Superior attachment of the transfected cells was observed in a comparison of recoverable protein, with an average of 113±2.3 μg protein/well (n=24) versus the untransfected cells with an average of 21.8±4.8 μg protein/well (n=12).

Numerous modifications and variations of the present invention are included in the above-identified specification and are expected to be obvious to one of skill in the art. Such modifications and alterations to the compositions and processes of the present invention are believed to be encompassed in the scope of the claims appended hereto.

    __________________________________________________________________________     #             SEQUENCE LISTING     - (1) GENERAL INFORMATION:     -    (iii) NUMBER OF SEQUENCES: 4     - (2) INFORMATION FOR SEQ ID NO:1:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 2028 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: double               (D) TOPOLOGY: Not Relev - #ant     -     (ii) MOLECULE TYPE: cDNA to mRNA     -     (ix) FEATURE:               (A) NAME/KEY: CDS               (B) LOCATION: 47..1402     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:1:     #GAG CAG        55TCAGT GCTGCTTTCT TTAGGACGAA AGAAGT ATG     #Gln            Met Glu     #                 1     - TGG GAT CAC TTT CAC AAT CAA CAG GAG GAC AC - #T GAT AGC TGC TCC GAA      103     Trp Asp His Phe His Asn Gln Gln Glu Asp Th - #r Asp Ser Cys Ser Glu     #      15     - TCT GTG AAA TTT GAT GCT CGC TCA ATG ACA GC - #T TTG CTT CCT CCG AAT      151     Ser Val Lys Phe Asp Ala Arg Ser Met Thr Al - #a Leu Leu Pro Pro Asn     # 35     - CCT AAA AAC AGC CCT TCC CTT CAA GAG AAA CT - #G AAG TCC TTC AAA GCT      199     Pro Lys Asn Ser Pro Ser Leu Gln Glu Lys Le - #u Lys Ser Phe Lys Ala     #                 50     - GCA CTG ATT GCC CTT TAC CTC CTC GTG TTT GC - #A GTT CTC ATC CCT CTC      247     Ala Leu Ile Ala Leu Tyr Leu Leu Val Phe Al - #a Val Leu Ile Pro Leu     #             65     - ATT GGA ATA GTG GCA GCT CAA CTC CTG AAG TG - #G GAA ACG AAG AAT TGC      295     Ile Gly Ile Val Ala Ala Gln Leu Leu Lys Tr - #p Glu Thr Lys Asn Cys     #         80     - TCA GTT AGT TCA ACT AAT GCA AAT GAT ATA AC - #T CAA AGT CTC ACG GGA      343     Ser Val Ser Ser Thr Asn Ala Asn Asp Ile Th - #r Gln Ser Leu Thr Gly     #     95     - AAA GGA AAT GAC AGC GAA GAG GAA ATG AGA TT - #T CAA GAA GTC TTT ATG      391     Lys Gly Asn Asp Ser Glu Glu Glu Met Arg Ph - #e Gln Glu Val Phe Met     100                 1 - #05                 1 - #10                 1 -     #15     - GAA CAC ATG AGC AAC ATG GAG AAG AGA ATC CA - #G CAT ATT TTA GAC ATG      439     Glu His Met Ser Asn Met Glu Lys Arg Ile Gl - #n His Ile Leu Asp Met     #               130     - GAA GCC AAC CTC ATG GAC ACA GAG CAT TTC CA - #A AAT TTC AGC ATG ACA      487     Glu Ala Asn Leu Met Asp Thr Glu His Phe Gl - #n Asn Phe Ser Met Thr     #           145     - ACT GAT CAA AGA TTT AAT GAC ATT CTT CTG CA - #G CTA AGT ACC TTG TTT      535     Thr Asp Gln Arg Phe Asn Asp Ile Leu Leu Gl - #n Leu Ser Thr Leu Phe     #       160     - TCC TCA GTC CAG GGA CAT GGG AAT GCA ATA GA - #T GAA ATC TCC AAG TCC      583     Ser Ser Val Gln Gly His Gly Asn Ala Ile As - #p Glu Ile Ser Lys Ser     #   175     - TTA ATA AGT TTG AAT ACC ACA TTG CTT GAT TT - #G CAG CTC AAC ATA GAA      631     Leu Ile Ser Leu Asn Thr Thr Leu Leu Asp Le - #u Gln Leu Asn Ile Glu     180                 1 - #85                 1 - #90                 1 -     #95     - AAT CTG AAT GGC AAA ATC CAA GAG AAT ACC TT - #C AAA CAA CAA GAG GAA      679     Asn Leu Asn Gly Lys Ile Gln Glu Asn Thr Ph - #e Lys Gln Gln Glu Glu     #               210     - ATC AGT AAA TTA GAG GAG CGT GTT TAC AAT GT - #A TCA GCA GAA ATT ATG      727     Ile Ser Lys Leu Glu Glu Arg Val Tyr Asn Va - #l Ser Ala Glu Ile Met     #           225     - GCT ATG AAA GAA GAA CAA GTG CAT TTG GAA CA - #G GAA ATA AAA GGA GAA      775     Ala Met Lys Glu Glu Gln Val His Leu Glu Gl - #n Glu Ile Lys Gly Glu     #       240     - GTG AAA GTA CTG AAT AAC ATC ACT AAT GAT CT - #C AGA CTG AAA GAT TGG      823     Val Lys Val Leu Asn Asn Ile Thr Asn Asp Le - #u Arg Leu Lys Asp Trp     #   255     - GAA CAT TCT CAG ACC TTG AGA AAT ATC ACT TT - #A ATT CAA GGT CCT CCT      871     Glu His Ser Gln Thr Leu Arg Asn Ile Thr Le - #u Ile Gln Gly Pro Pro     260                 2 - #65                 2 - #70                 2 -     #75     - GGA CCC CCG GGT GAA AAA GGA GAT CGA GGT CC - #C ACT GGA GAA AGT GGT      919     Gly Pro Pro Gly Glu Lys Gly Asp Arg Gly Pr - #o Thr Gly Glu Ser Gly     #               290     - CCA CGA GGA TTT CCA GGT CCA ATA GGT CCT CC - #G GGT CTT AAA GGT GAT      967     Pro Arg Gly Phe Pro Gly Pro Ile Gly Pro Pr - #o Gly Leu Lys Gly Asp     #           305     - CGG GGA GCA ATT GGC TTT CCT GGA AGT CGA GG - #A CTC CCA GGA TAT GCC     1015     Arg Gly Ala Ile Gly Phe Pro Gly Ser Arg Gl - #y Leu Pro Gly Tyr Ala     #       320     - GGA AGG CCA GGA AAT TCT GGA CCA AAA GGC CA - #G AAA GGG GAA AAG GGG     1063     Gly Arg Pro Gly Asn Ser Gly Pro Lys Gly Gl - #n Lys Gly Glu Lys Gly     #   335     - AGT GGA AAC ACA TTA ACT CCA TTT ACG AAA GT - #T CGA CTG GTC GGT GGG     1111     Ser Gly Asn Thr Leu Thr Pro Phe Thr Lys Va - #l Arg Leu Val Gly Gly     340                 3 - #45                 3 - #50                 3 -     #55     - AGC GGC CCT CAC GAG GGG AGA GTG GAG ATA CT - #C CAC AGC GGC CAG TGG     1159     Ser Gly Pro His Glu Gly Arg Val Glu Ile Le - #u His Ser Gly Gln Trp     #               370     - GGT ACA ATT TGT GAC GAT CGC TGG GAA GTG CG - #C GTT GGA CAG GTC GTC     1207     Gly Thr Ile Cys Asp Asp Arg Trp Glu Val Ar - #g Val Gly Gln Val Val     #           385     - TGT AGG AGC TTG GGA TAC CCA GGT GTT CAA GC - #C GTG CAC AAG GCA GCT     1255     Cys Arg Ser Leu Gly Tyr Pro Gly Val Gln Al - #a Val His Lys Ala Ala     #       400     - CAC TTT GGA CAA GGT ACT GGT CCA ATA TGG CT - #G AAT GAA GTG TTT TGT     1303     His Phe Gly Gln Gly Thr Gly Pro Ile Trp Le - #u Asn Glu Val Phe Cys     #   415     - TTT GGG AGA GAA TCA TCT ATT GAA GAA TGT AA - #A ATT CGG CAA TGG GGG     1351     Phe Gly Arg Glu Ser Ser Ile Glu Glu Cys Ly - #s Ile Arg Gln Trp Gly     420                 4 - #25                 4 - #30                 4 -     #35     - ACA AGA GCC TGT TCA CAT TCT GAA GAT GCT GG - #A GTC ACT TGC ACT TTA     1399     Thr Arg Ala Cys Ser His Ser Glu Asp Ala Gl - #y Val Thr Cys Thr Leu     #               450     - TAA TGCATCATAT TTTCATTCAC AACTATGAAA TCGCTGCTCA AAAATGATT - #T     1452      *     - TATTACCTTG TTCCTGTAAA ATCCATTTAA TCAATATTTA AGAGATTAAG AA - #TATTGCCC     1512     - AAATAATATT TTAGATTACA GGATTAATAT ATTGAACACC TTCATGCTTA CT - #ATTTTATG     1572     - TCTATATTTA AATCATTTTA ACTTCTATAG GTTTTTAAAT GGAATTTTCT AA - #TATAATGA     1632     - CTTATATGCT GAATTGAACA TTTTGAAGTT TATAGCTTCC AGATTACAAA GG - #CCAAGGGT     1692     - AATAGAAATG CATACCAGTA ATTGGCTCCA ATTCATAATA TGTTCACCAG GA - #GATTACAA     1752     - TTTTTTGCTC TTCTTGTCTT TGTAATCTAT TTAGTTGATT TTAATTACTT TC - #TGAATAAC     1812     - GGAAGGGATC AGAAGATATC TTTTGTGCCT AGATTGCAAA ATCTCCAATC CA - #CACATATT     1872     - GTTTTAAAAT AAGAATGTTA TCCAACTATT AAGATATCTC AATGTGCAAT AA - #CTTGTGTA     1932     - TTAGATATCA ATGTTAATGA TATGTCTTGG CCACTATGGA CCAGGGAGCT TA - #TTTTTCTT     1992     #     2028         TGTT TAATTGAATC ATGAAG     - (2) INFORMATION FOR SEQ ID NO:2:     -      (i) SEQUENCE CHARACTERISTICS:               (A) LENGTH:  451 ami - #no acids               (B) TYPE: amino acid               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: protein     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:2:     - Met Glu Gln Trp Asp His Phe His Asn Gln Gl - #n Glu Asp Thr Asp Ser     #                 15     - Cys Ser Glu Ser Val Lys Phe Asp Ala Arg Se - #r Met Thr Ala Leu Leu     #             30     - Pro Pro Asn Pro Lys Asn Ser Pro Ser Leu Gl - #n Glu Lys Leu Lys Ser     #         45     - Phe Lys Ala Ala Leu Ile Ala Leu Tyr Leu Le - #u Val Phe Ala Val Leu     #     60     - Ile Pro Leu Ile Gly Ile Val Ala Ala Gln Le - #u Leu Lys Trp Glu Thr     # 80     - Lys Asn Cys Ser Val Ser Ser Thr Asn Ala As - #n Asp Ile Thr Gln Ser     #                 95     - Leu Thr Gly Lys Gly Asn Asp Ser Glu Glu Gl - #u Met Arg Phe Gln Glu     #           110     - Val Phe Met Glu His Met Ser Asn Met Glu Ly - #s Arg Ile Gln His Ile     #       125     - Leu Asp Met Glu Ala Asn Leu Met Asp Thr Gl - #u His Phe Gln Asn Phe     #   140     - Ser Met Thr Thr Asp Gln Arg Phe Asn Asp Il - #e Leu Leu Gln Leu Ser     145                 1 - #50                 1 - #55                 1 -     #60     - Thr Leu Phe Ser Ser Val Gln Gly His Gly As - #n Ala Ile Asp Glu Ile     #               175     - Ser Lys Ser Leu Ile Ser Leu Asn Thr Thr Le - #u Leu Asp Leu Gln Leu     #           190     - Asn Ile Glu Asn Leu Asn Gly Lys Ile Gln Gl - #u Asn Thr Phe Lys Gln     #       205     - Gln Glu Glu Ile Ser Lys Leu Glu Glu Arg Va - #l Tyr Asn Val Ser Ala     #   220     - Glu Ile Met Ala Met Lys Glu Glu Gln Val Hi - #s Leu Glu Gln Glu Ile     225                 2 - #30                 2 - #35                 2 -     #40     - Lys Gly Glu Val Lys Val Leu Asn Asn Ile Th - #r Asn Asp Leu Arg Leu     #               255     - Lys Asp Trp Glu His Ser Gln Thr Leu Arg As - #n Ile Thr Leu Ile Gln     #           270     - Gly Pro Pro Gly Pro Pro Gly Glu Lys Gly As - #p Arg Gly Pro Thr Gly     #       285     - Glu Ser Gly Pro Arg Gly Phe Pro Gly Pro Il - #e Gly Pro Pro Gly Leu     #   300     - Lys Gly Asp Arg Gly Ala Ile Gly Phe Pro Gl - #y Ser Arg Gly Leu Pro     305                 3 - #10                 3 - #15                 3 -     #20     - Gly Tyr Ala Gly Arg Pro Gly Asn Ser Gly Pr - #o Lys Gly Gln Lys Gly     #               335     - Glu Lys Gly Ser Gly Asn Thr Leu Thr Pro Ph - #e Thr Lys Val Arg Leu     #           350     - Val Gly Gly Ser Gly Pro His Glu Gly Arg Va - #l Glu Ile Leu His Ser     #       365     - Gly Gln Trp Gly Thr Ile Cys Asp Asp Arg Tr - #p Glu Val Arg Val Gly     #   380     - Gln Val Val Cys Arg Ser Leu Gly Tyr Pro Gl - #y Val Gln Ala Val His     385                 3 - #90                 3 - #95                 4 -     #00     - Lys Ala Ala His Phe Gly Gln Gly Thr Gly Pr - #o Ile Trp Leu Asn Glu     #               415     - Val Phe Cys Phe Gly Arg Glu Ser Ser Ile Gl - #u Glu Cys Lys Ile Arg     #           430     - Gln Trp Gly Thr Arg Ala Cys Ser His Ser Gl - #u Asp Ala Gly Val Thr     #       445     - Cys Thr Leu         450     - (2) INFORMATION FOR SEQ ID NO:3:     -      (i) SEQUENCE CHARACTERISTICS:     #pairs    (A) LENGTH: 1367 base               (B) TYPE: nucleic acid               (C) STRANDEDNESS: double               (D) TOPOLOGY: Not Relev - #ant     -     (ii) MOLECULE TYPE: cDNA to mRNA     -     (ix) FEATURE:               (A) NAME/KEY: CDS               (B) LOCATION: 67..1143     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:3:     - TAGGTTTCAA TTGTAAAGAG AGAGAAGTGG ATAAATCAGT GCTGCTTTCT TT - #AGGACGAA       60     #CAA CAG GAG GAC ACT       108AC TTT CAC AAT            Met Glu Gln Trp Asp His Ph - #e His Asn Gln Gln Glu Asp Thr     #      10     - GAT AGC TGC TCC GAA TCT GTG AAA TTT GAT GC - #T CGC TCA ATG ACA GCT      156     Asp Ser Cys Ser Glu Ser Val Lys Phe Asp Al - #a Arg Ser Met Thr Ala     # 30     - TTG CTT CCT CCG AAT CCT AAA AAC AGC CCT TC - #C CTT CAA GAG AAA CTG      204     Leu Leu Pro Pro Asn Pro Lys Asn Ser Pro Se - #r Leu Gln Glu Lys Leu     #                 45     - AAG TCC TTC AAA GCT GCA CTG ATT GCC CTT TA - #C CTC CTC GTG TTT GCA      252     Lys Ser Phe Lys Ala Ala Leu Ile Ala Leu Ty - #r Leu Leu Val Phe Ala     #             60     - GTT CTC ATC CCT CTC ATT GGA ATA GTG GCA GC - #T CAA CTC CTG AAG TGG      300     Val Leu Ile Pro Leu Ile Gly Ile Val Ala Al - #a Gln Leu Leu Lys Trp     #         75     - GAA ACG AAG AAT TGC TCA GTT AGT TCA ACT AA - #T GCA AAT GAT ATA ACT      348     Glu Thr Lys Asn Cys Ser Val Ser Ser Thr As - #n Ala Asn Asp Ile Thr     #     90     - CAA AGT CTC ACG GGA AAA GGA AAT GAC AGC GA - #A GAG GAA ATG AGA TTT      396     Gln Ser Leu Thr Gly Lys Gly Asn Asp Ser Gl - #u Glu Glu Met Arg Phe     #110     - CAA GAA GTC TTT ATG GAA CAC ATG AGC AAC AT - #G GAG AAG AGA ATC CAG      444     Gln Glu Val Phe Met Glu His Met Ser Asn Me - #t Glu Lys Arg Ile Gln     #               125     - CAT ATT TTA GAC ATG GAA GCC AAC CTC ATG GA - #C ACA GAG CAT TTC CAA      492     His Ile Leu Asp Met Glu Ala Asn Leu Met As - #p Thr Glu His Phe Gln     #           140     - AAT TTC AGC ATG ACA ACT GAT CAA AGA TTT AA - #T GAC ATT CTT CTG CAG      540     Asn Phe Ser Met Thr Thr Asp Gln Arg Phe As - #n Asp Ile Leu Leu Gln     #       155     - CTA AGT ACC TTG TTT TCC TCA GTC CAG GGA CA - #T GGG AAT GCA ATA GAT      588     Leu Ser Thr Leu Phe Ser Ser Val Gln Gly Hi - #s Gly Asn Ala Ile Asp     #   170     - GAA ATC TCC AAG TCC TTA ATA AGT TTG AAT AC - #C ACA TTG CTT GAT TTG      636     Glu Ile Ser Lys Ser Leu Ile Ser Leu Asn Th - #r Thr Leu Leu Asp Leu     175                 1 - #80                 1 - #85                 1 -     #90     - CAG CTC AAC ATA GAA AAT CTG AAT GGC AAA AT - #C CAA GAG AAT ACC TTC      684     Gln Leu Asn Ile Glu Asn Leu Asn Gly Lys Il - #e Gln Glu Asn Thr Phe     #               205     - AAA CAA CAA GAG GAA ATC AGT AAA TTA GAG GA - #G CGT GTT TAC AAT GTA      732     Lys Gln Gln Glu Glu Ile Ser Lys Leu Glu Gl - #u Arg Val Tyr Asn Val     #           220     - TCA GCA GAA ATT ATG GCT ATG AAA GAA GAA CA - #A GTG CAT TTG GAA CAG      780     Ser Ala Glu Ile Met Ala Met Lys Glu Glu Gl - #n Val His Leu Glu Gln     #       235     - GAA ATA AAA GGA GAA GTG AAA GTA CTG AAT AA - #C ATC ACT AAT GAT CTC      828     Glu Ile Lys Gly Glu Val Lys Val Leu Asn As - #n Ile Thr Asn Asp Leu     #   250     - AGA CTG AAA GAT TGG GAA CAT TCT CAG ACC TT - #G AGA AAT ATC ACT TTA      876     Arg Leu Lys Asp Trp Glu His Ser Gln Thr Le - #u Arg Asn Ile Thr Leu     255                 2 - #60                 2 - #65                 2 -     #70     - ATT CAA GGT CCT CCT GGA CCC CCG GGT GAA AA - #A GGA GAT CGA GGT CCC      924     Ile Gln Gly Pro Pro Gly Pro Pro Gly Glu Ly - #s Gly Asp Arg Gly Pro     #               285     - ACT GGA GAA AGT GGT CCA CGA GGA TTT CCA GG - #T CCA ATA GGT CCT CCG      972     Thr Gly Glu Ser Gly Pro Arg Gly Phe Pro Gl - #y Pro Ile Gly Pro Pro     #           300     - GGT CTT AAA GGT GAT CGG GGA GCA ATT GGC TT - #T CCT GGA AGT CGA GGA     1020     Gly Leu Lys Gly Asp Arg Gly Ala Ile Gly Ph - #e Pro Gly Ser Arg Gly     #       315     - CTC CCA GGA TAT GCC GGA AGG CCA GGA AAT TC - #T GGA CCA AAA GGC CAG     1068     Leu Pro Gly Tyr Ala Gly Arg Pro Gly Asn Se - #r Gly Pro Lys Gly Gln     #   330     - AAA GGG GAA AAG GGG AGT GGA AAC ACA TTA AG - #A CCA GTA CAA CTC ACT     1116     Lys Gly Glu Lys Gly Ser Gly Asn Thr Leu Ar - #g Pro Val Gln Leu Thr     335                 3 - #40                 3 - #45                 3 -     #50     - GAT CAT ATT AGG GCA GGG CCC TCT TAA GATCAGGTG - #G GTTGGGCGGG     1163     Asp His Ile Arg Ala Gly Pro Ser  *                     355     - ACATCCTCTG CTACCATCTC ATTAAAAGGC CCTTCACCTC TGGACAAGTC AT - #CTGCAACA     1223     - ACTGACTTCC AAGATCCTTT TGTGACTCCT CCAAATGACT TTGGTTCCCG TG - #TTGTACCT     1283     - GACTTCCACA TGGCCTTCTC TCCTGGTCCC TGGTGCTGTT TGGGCCTCTG CT - #CCCATGCT     1343     #              1367CCAA TTAC     - (2) INFORMATION FOR SEQ ID NO:4:     -      (i) SEQUENCE CHARACTERISTICS:               (A) LENGTH:  358 ami - #no acids               (B) TYPE: amino acid               (D) TOPOLOGY: linear     -     (ii) MOLECULE TYPE: protein     -     (xi) SEQUENCE DESCRIPTION: SEQ ID NO:4:     - Met Glu Gln Trp Asp His Phe His Asn Gln Gl - #n Glu Asp Thr Asp Ser     #                 15     - Cys Ser Glu Ser Val Lys Phe Asp Ala Arg Se - #r Met Thr Ala Leu Leu     #             30     - Pro Pro Asn Pro Lys Asn Ser Pro Ser Leu Gl - #n Glu Lys Leu Lys Ser     #         45     - Phe Lys Ala Ala Leu Ile Ala Leu Tyr Leu Le - #u Val Phe Ala Val Leu     #     60     - Ile Pro Leu Ile Gly Ile Val Ala Ala Gln Le - #u Leu Lys Trp Glu Thr     # 80     - Lys Asn Cys Ser Val Ser Ser Thr Asn Ala As - #n Asp Ile Thr Gln Ser     #                 95     - Leu Thr Gly Lys Gly Asn Asp Ser Glu Glu Gl - #u Met Arg Phe Gln Glu     #           110     - Val Phe Met Glu His Met Ser Asn Met Glu Ly - #s Arg Ile Gln His Ile     #       125     - Leu Asp Met Glu Ala Asn Leu Met Asp Thr Gl - #u His Phe Gln Asn Phe     #   140     - Ser Met Thr Thr Asp Gln Arg Phe Asn Asp Il - #e Leu Leu Gln Leu Ser     145                 1 - #50                 1 - #55                 1 -     #60     - Thr Leu Phe Ser Ser Val Gln Gly His Gly As - #n Ala Ile Asp Glu Ile     #               175     - Ser Lys Ser Leu Ile Ser Leu Asn Thr Thr Le - #u Leu Asp Leu Gln Leu     #           190     - Asn Ile Glu Asn Leu Asn Gly Lys Ile Gln Gl - #u Asn Thr Phe Lys Gln     #       205     - Gln Glu Glu Ile Ser Lys Leu Glu Glu Arg Va - #l Tyr Asn Val Ser Ala     #   220     - Glu Ile Met Ala Met Lys Glu Glu Gln Val Hi - #s Leu Glu Gln Glu Ile     225                 2 - #30                 2 - #35                 2 -     #40     - Lys Gly Glu Val Lys Val Leu Asn Asn Ile Th - #r Asn Asp Leu Arg Leu     #               255     - Lys Asp Trp Glu His Ser Gln Thr Leu Arg As - #n Ile Thr Leu Ile Gln     #           270     - Gly Pro Pro Gly Pro Pro Gly Glu Lys Gly As - #p Arg Gly Pro Thr Gly     #       285     - Glu Ser Gly Pro Arg Gly Phe Pro Gly Pro Il - #e Gly Pro Pro Gly Leu     #   300     - Lys Gly Asp Arg Gly Ala Ile Gly Phe Pro Gl - #y Ser Arg Gly Leu Pro     305                 3 - #10                 3 - #15                 3 -     #20     - Gly Tyr Ala Gly Arg Pro Gly Asn Ser Gly Pr - #o Lys Gly Gln Lys Gly     #               335     - Glu Lys Gly Ser Gly Asn Thr Leu Arg Pro Va - #l Gln Leu Thr Asp His     #           350     - Ile Arg Ala Gly Pro Ser             355     __________________________________________________________________________ 

What is claimed is:
 1. A method of screening a compound for the ability to affect the biological activity of a protein comprising the steps of:(a) providing on a solid support human embryonic kidney 293 cells co-transfected with a mammalian macrophage scavenger receptor gene and a second selected gene which encodes said protein having known biological activity; (b) measuring the expression of the protein encoded by said second selected gene; (c) incubating said co-transfected 293 cells in the presence of said compound; (d) screening the cells of (c) for the ability of the compound to affect said biological activity.
 2. The method according to claim 1, wherein the receptor gene is a human macrophage scavenger receptor gene selected from the group consisting of: Type I and Type II.
 3. An improved method for screening a compound for the ability to affect the biological activity of a protein comprising measuring in a transfected cell the expression of said protein encoded by a selected gene; incubating said transfected cell in the presence of a compound; and screening the cell for the ability of said compound to affect said biological activity, the improvement comprising employing as said transfected cell, human embryonic kidney 293 cells co-transfected with a mammalian macrophage scavenger receptor gene and said selected gene, said cells attached to a solid support.
 4. An improved method for performing a biological assay on a cell attached to a solid support, wherein said assay involves at least one washing step, said improvement comprising employing as said attached cell, human embryonic kidney 293 cells co-transfected with a mammalian macrophage scavenger receptor gene.
 5. An improved method for measuring the production of a protein in a cell attached to a solid support, said improvement comprising employing as said attached cell, human embryonic kidney 293 cells co-transfected with a mammalian macrophage scavenger receptor gene.
 6. The method according to claim 3, wherein the receptor gene is a human macrophage scavenger receptor gene selected from the group consisting of: Type I and Type II.
 7. The method according to claim 4, wherein the receptor gene is a human macrophage scavenger receptor gene selected from the group consisting of: Type I and Type II.
 8. The method according to claim 5, wherein the receptor gene is a human macrophage scavenger receptor gene selected from the group consisting of: Type I and Type II. 